Fin seal containers have been used as alternatives to extruded plastic containers, cans and the like for packaging various products, such as consumer goods and food-stuffs. For example, fin seal containers constructed from paperboard-based substrates having a sufficient barrier layer (e.g., a moisture barrier layer and/or an oxygen barrier layer) have been used to package liquid food-stuffs, such as milk and soup, as well as dry food-stuffs, such as grains and cereals.
Fin seal containers are traditionally formed from a pre-cut substrate blank, such as a pre-cut paperboard blank. Two ends of the blank are typically connected at a seam to form a three-dimensional (e.g., tubular) structure having an internal volume that is open at opposite ends of the structure. During packaging, a first open end of the structure is typically sealed, such as with a fin seal, to partially enclose the internal volume prior to introducing the product. Then, the product is introduced to the internal volume of the structure by way of the second open end. Finally, once the internal volume has been filled as desired, the second open end is sealed with a fin seal.
Traditionally, fin seal containers are formed from substrates that have been coated on their inner and/or outer surfaces with a heat-sealable material. Therefore, the fin seal may be formed by pressing two opposing end portions of the container structure between heated platens for a sufficient amount of time. During the pressing operation, heat from the platens is transferred through the substrate to melt (or at least tackify) the heat-sealable material such that the pressure applied by the heated platens bonds together the two opposing end portions of the container structure to form a fin-shaped seal.
Thus, the speed at which product may be packaged is limited by the sealing step, specifically the time required to transfer sufficient heat from the heated platens to the heat-sealable material on the inner surface of the substrate. While increasing the surface temperature of the heated platens may increase heat flux and, thus, speed-up the packaging process, platen temperatures that are too high may degrade or damage the package.
Accordingly, those skilled in the art continue with research and development efforts in the field of fin seal containers.